The invention is directed to a process for the production of cationic starch ethers by reacting starch with an alkylidene epoxide in alkaline medium in the presence of water.
It is known to cationize starch or starch containing substances by reaction with cationic etherifying agents. The reaction is particularly carried out in the presence of small amounts of water at room temperature or up to 200.degree. C. with alkylidene epoxides which have a tertiary amino group or a quaternary ammonium group (Caesar U.S. Pat. No. 3,422,087 and Billy U.S. Pat. No. 3,448,101; the entire disclosure of the Caesar and Billy patents are hereby incorporated by reference) or in the presence of only small amounts of water with addition of, in a given case, halogenated hydrocarbons and with addition of strongly alkaline acting materials at temperatures of 30.degree. to 80.degree. C. with halogenated tertiary amines or quaternary ammonium salts or alkylidene epoxides which have a tertiary amino group or a quaternary ammonium group (Caesar U.S. Pat. No. 3,243,426) or in the presence of large amounts of water with addition of strongly alkaline acting materials at room temperature or slightly elevated temperature with alkylidene epoxides or alkylidene halohydrins which have a quaternary ammonium group (Paschall U.S. Pat. No. 2,876,217 or Schildneck U.S. Pat. No. 3,346,563; the entire disclosure of the Paschall and Schildneck patents is hereby incorporated by reference). In all known processes the yields of etherified starch, based on the amount of etherifying agent employed are unsatisfactory.